The defects in white blood cell differentiation and function associated with leukemia and other diseases will be studied by high resolution electron microscopy and cytochemistry, and cell fractionation procedures. We will investigate the following problems: a) the fine structure and distribution of granule enzymes within organelles of leukemic cells from man and experimental animals; b) normal granulopoiesis in human fetus and newborn; c) reconstitution of damaged bone marrow; d) the effects of inflammation on granulopoiesis in man; e) extend our studies on phagocytosis and function of normal PMN to abnormal cells.